1. Field of the Invention
The present invention relates to the mechanical arts. In particular, the present invention relates to a sorbent assembly for use with sorbent-driven cooling devices.
2. Discussion of the Related Art
There have been many attempts to manufacture an inexpensive, lightweight, compact cooling device that employs an adsorbent to adsorb a liquid refrigerant such as water. In such a cooling device, there are typically two chambers, one housing the adsorbent and the other housing the liquid refrigerant, in thermal contact with the medium to be cooled. To achieve an effective cooling action, both the adsorbent chamber and the liquid refrigerant chamber must be evacuated. The adsorbent chamber, in particular, must have a substantial vacuum condition (evacuated to less than 8xc3x9710xe2x88x924 mm Hg). When communication is opened between the two chambers, some of the liquid refrigerant is caused to vaporize and flow into the adsorbent chamber, where the vapor is adsorbed by the adsorbent. The latent heat of vaporization causes heat to be removed from the media adjacent the liquid. The adsorption of the vapor causes additional liquid to be vaporized, thus further continuing the cooling process.
One particular application for which adsorbent-driven cooling devices have been considered is for the rapid chilling of a beverage. One such device is described in U.S. Pat. No. 4,928,495. This patent describes a self-contained cooling device in which a cooling effect is produced by causing a liquid refrigerant to evaporate in a chamber within a beverage container and in the process absorb heat from its surroundings. The resulting refrigerant vapor is then adsorbed by an adsorbent housed in a chamber located outside of the beverage container. While this device may act to cool a beverage placed within the container, the difficulties and costs associated with manufacturing a beverage container with an external adsorbent chamber are a significant impediment to mass production of such containers. In addition, with this arrangement, the path in which the vaporized liquid must travel before it is adsorbed by the adsorbent is long, which prevents the cooling device, from adequately cooling the beverage within a commercially acceptable amount of time.
Another beverage cooling device is described in U.S. Pat. No. 6,151,911. This patent describes a mechanism for cooling a contained beverage by use of an absorption or adsorption substrate in thermal contact with a phase change medium. It is a drawback of this cooling device in that it requires a cylindrical chamber with a lengthy vapor pathway to avoid liquid contact from the phase change medium with the adsorption or adsorption substrate.
Accordingly, it should be recognized that there remains a need for an adsorbent assembly and cooling device that is easy and inexpensive to manufacture, is compact and lightweight, and has a short vapor path while providing effective cooling characteristics. The present invention satisfies these and other needs.
The invention resides in an evacuated sorbent assembly and cooling device that provide advantages over known adsorbent-driven cooling devices in that the invention is easy and inexpensive to manufacture. Also, the invention is compact and lightweight, and has a short vapor path. Additionally, the invention provides effective cooling characteristics.
The present invention is embodied in an evacuated sorbent assembly for coupling to a liquid refrigerant reservoir and a cooling device comprised of at least one sorbent section, at least one liquid passageway section, and an actuator. The sorbent section contains a sorbent for a liquid refrigerant. The liquid passageway section is adjacent the sorbent section and defines a liquid passageway through a portion of the evacuated sorbent assembly or cooling device to the sorbent section. The liquid passageway contains wicking material of an amount sufficient to prevent the liquid refrigerant from contacting the sorbent. The actuator controls liquid communication between the liquid passageway section and the liquid refrigerant reservoir. In another embodiment, the evacuated sorbent assembly includes a vapor-permeable membrane that separates adjacent sorbent and liquid passageway sections whether or not the liquid passageway section contains wicking material.
Embodiments of the cooling device additionally include a liquid refrigerant reservoir, adjacent the liquid passageway section, and a casing that surrounds the sorbent section, the liquid passageway section, the vapor-permeable membrane, the liquid refrigerant reservoir, and the actuator.
In addition to including a wicking material, other embodiments of the present invention include: a heat-removing material, which may be a phase-changing material, in thermal contact with the sorbent; at least one liquid barrier between the heat-removing material and the sorbent; and at least one thermal spacer positioned between the sorbent section and the liquid passageway section. In some embodiments, the thermal spacer is interposed between the sorbent section and the vapor-permeable membrane. In other embodiments, the thermal spacer is interposed between the vapor-permeable membrane and the liquid passageway section. In another embodiment (FIG. 10) there is no wicking material, nor vapor permeable membrane, but rather an anisotropic insulation material hydrophobic on one side and hydrophilic on the other replaces the functions of those components. Furthermore, some embodiments include casings made from a flexible material such as a metallicized plastic.
A feature of the present invention is that it is compact and lightweight. The invention is designed to fit within a host container, i.e., a beverage container. An additional feature of the invention, related to its compact size, is the short vapor path between the liquid refrigerant reservoir and the sorbent. The vapor path is at most several millimeters.
Other features and advantages of the present invention will be set forth, in part, in the description which follows and the accompanying drawings, wherein the preferred embodiments of the present invention are described and shown, and in part will become apparent to those skilled in the art upon examination of the following detailed description taken in conjunction with the accompanying drawings, or may be learned by practice of the present invention. The advantages of the present invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.